1. The Field of the Invention
The invention described relates primarily to novel polyamines that are useful in the manufacture of paper and paperboard; more particularly, it relates to a cationic resin comprising a cross-linked polyamine containing secondary amine groups and having pendant from at least some of the secondary amine groups a tertiary or quaternary amine groups. This invention also relates to dispersed fortified rosin sizing agents including these novel polyamines as stabilizers for the dispersion, and to drainage aids incorporating these novel resins.
2. The State of the Art
Paper and related paper products are made from cellulosic fibers. In paper and paperboard processing, present high speed machines generally include a web (i.e., a porous conveyor) moving at speeds on the order of one kilometer per minute. A dilute suspension of cellulosic fibers is furnished and accelerated during application to the web; that is, effectively the "furnish" is sprayed onto the web. After a distance of about 50 m from the spraying operation, a vacuum is applied to the bottom side of the web to drain water from the suspension and produce a wet laid paper sheet. Generally, the solids content of the furnish is 1-4 wt. %, which is increased by dewatering to about 40 wt. %. Thereafter, this wet sheet is dried to form finished paper and paperboard. The water that is drained from this stock dispersion during the formation of the wet laid paper sheet may be recycled to the stock preparation plant for reuse in the preparation of additional quantities of the paper stock dispersion.
Modern paper mills tend to close their water systems in order to lower economic costs and lower environmental contamination by minimizing both the amount of polluted water released from the mill and the make-up fresh water taken into the mill. Additionally, compounds such as fillers, dyes, sizing agents, wet and dry strength-enhancing resins, retention aids, defoamers, and other additives are widely used in manufacturing paper and paperboard. These additives are now typically added to the low solids paper stock dispersion or to various subsequent stages of processing (termed "internal" incorporation of the additive) rather than to the finished product (an "external" addition). The water in such a closed mill system tends to become loaded with cellulose fines and these chemical additives, which soon begin to reduce the rate of dewatering. Chemicals generically termed drainage aids have been developed to accelerate the dewatering of these stock dispersions. While drainage aids may be used in open water systems, their greater utility is found in closed water systems to accelerate dewatering and to speed up the paper machine towards maximizing paper production. The efficiencies of drainage aids vary with the particular type of paper furnish used; the furnish may vary between the extremes of a 100% virgin furnish to a 100% waste paper furnish.
The effects of the various chemical additives on the dewatering process on paper and board machines have been widely investigated. Kartovaara reported in Zellstoff Paperforschungainst (SF-00101, Helsinki, Finland) that a nonionic and an anionic polymer such as a polyoxyethylene and a carboxymethyl cellulose (CMC) impair the dewatering of a wet paper web made from secondary and sulphate pulps in wet pressing, whereas cationic polymers, e.g., cationic starch and polyethyleneimine, accelerate the dewatering. However, differential scanning calorimetric measurements indicated that these two cationic polymers work in different ways. The effect of the cationic starch was shown to be retained even at long pressing times indicating that its effect on the change of filtration resistance of the wet paper web is not reduced. The effect of the polyethyleneimine on the wet pressing disappeared with increasing pressing time because its effect is combined with the filtration properties of the wet web.
Cationic starches have been made using different cationizing agents. German OLS (Offenlegungsschrift) 3604796 discloses the use of the following cationizing agents for starch: ##STR1## where R.sub.1, R.sub.2 and R.sub.3 are C.sub.1-4 alkyl, n is 1-3, and X is Cl, Br, AcO (acetate), or sulphate. These cationizing agents have been used also with polyvinyl alcohol (DE 3626662) to yield dry strength additives for paper, and with galactomannans (DE 3604795) to yield other products useful in paper manufacture.
Cationizing agents of a similar type have been used with carboxylate polymers as in EP-A 187,281 to yield cationic water soluble polymers said to be useful as flocculation and filtration agents in paper manufacture. These same cationizing agents have been used with cellulose to form products useful in antistatic paper coatings (JP Kokai 79-87787), with lignosulphonic acid to form emulsifying agents for asphalt (DE OLS 2,218,144), with methacrylyloxypropylammonium salts to form sizing and wet strength agents for paper and textiles (U.S. Pat. No. 3,347,832), and with methacrylamide based polymers to form flocculents and oil well drilling additives (EP-A 156,646).
Polyethyleneimine and derivatives of polyethyleneimine are well known as drainage and retention aids in the manufacture of paper. German OLS 3519357 describes products prepared by the reaction of polyethyleneimine with polyvinyl alcohol and aldehydes.
It is known that drainage and retention aids can be made by crosslinking both polyamines and polyamidoamines. German OLS 1,570,296 discloses products made by crosslinking polyamines with epichlorohydrin. German OLS 1,795,392 discloses products made by reacting polyamidoamines with bifunctional crosslinking agents which are prepared by reacting a bis-tert-amine or a secondary amine with epichlorohydrin. German OLS 2434816 discloses a process for manufacturing paper additives wherein polyamidoamines, to which ethyleneimine is optionally grafted, are reacted with .alpha.,.omega.-dichlorohydrin ethers of polyalkylene oxides (i.e., having chlorine on each end of the molecule).
U.S. Pat. No. 2,926,116 and U.S. Pat. No. 2,926,154 describe a cationic thermosetting polyamide-epichlorohydrin resin and its use as a wet strength enhancer in paper making. The resin is formed by reacting a dicarboxylic acid with a polyalkylene polyamine to produce --NH(C.sub.n H.sub.2n NH).sub.x --CORCO--, wherein n and x are each 2 or more and R is the divalent organic radical of the dicarboxylic acid, and thereafter reacting that polymer with epichlorohydrin. An example of such wet strength resins is one derived from adipic acid and diethylenetriamine, --[--NHCH.sub.2 CH.sub.2 --NH--CH.sub.2 CH.sub.2 NH--CO--(CH.sub.2).sub.4 --CO--].sub.x --, and then reacted with epichlorohydrin to produce ##STR2## which is then heated to provide a polymer of the form ##STR3## The heterocyclic quaternary amine group is referred to as an azetidinium ring.
The art is thus still concerned with the problem of providing chemical additives which function especially in the neutral to alkaline pH regime for making paper and paperboard. ("Paperboard" is generally considered a lower grade paper product, such as used for making various types of "cardboard".) As noted for closed water systems, additives tend to accumulate in the water, including those additives intended to be incorporated into the paper product but which are not entirely fixed in the wet laid sheet.
Another additive commonly used in the manufacture of paper products is a sizing agent. Sizing is typically accomplished by adding a rosin-based sizing composition at one or more selected points in the paper machine, after which papermaker's alum (aluminum sulfate, or a similar salt) is commonly added to the sheet to precipitate the sizing agent onto the cellulosic fibers. This general technique of using a rosin-based sizing agent and alum has been practiced for many decades. However, the technique operates satisfactorily only at pH values lying between about 4 and 6; there exist cellulose pulps which are difficult to size under these pH conditions.
Another consideration with acid sizing is that paper made under acidic conditions not only develops less dry strength but, over time, the strength of the paper decreases. Yet another consideration in processing in such a system is acid-induced corrosion of the papermaking apparatus. Accumulation of acid is a particular concern with modern plants that recycle the drained water.
To accomplish sizing in a higher pH regime, some artisans have employed reactive sizes, such as alkyl ketene dimer or alkyl succinyl anhydride. Still, there are methods of using rosin-based sizes at more neutral pH conditions.
Rosins used in sizing compositions are usually comprised of wood rosin, gum rosin, tall oil rosin, or some mixture thereof. The rosin may be "fortified" by reaction with, for example, fumaric acid to form the fortified rosin (a Diels-Alder adduct of the original rosin).
U.S. Pat. No. 3,186,900 discloses a sizing composition used in the pH range of 6.0 to 7.5. These sizes comprise a relatively small amount of alum and a preblend of rosin size and a cationic polyamide-epichlorohydrin resin.
British Pat. No. 1,266,829 describes high-free-rosin emulsion sizes having 80-98% of the total solids weight comprising an unsaponified rosin. These sizes are used in the pH regime of 6.0-7.5. The composition also includes a water-soluble cellulose-substantive cationic polyamine, such as polyethylene imine, cationic starches polyvinylamine, polyvinylpyridine, poly(N-methyl pyridinium) chloride, urea-formaldehyde-poly-alkylene-polyamine, and aminopolyamide-epichlorohydrin resins.
EP-B-074,544 describes the preparation of fortified rosin dispersions in aqueous media, particularly a mixture of two dispersions based respectively on rosin and alkyl ketene dimer.
EP-292,975 discloses a cationic rosin size particularly for increasing the resistance to penetration of liquid packaging board by aggressive penetrants through ingress at the edges of the packaging board.
EP-208,667 discloses the use of a cationic surfactant in the preparation of rosin and synthetic size mixtures which are described as having a lower softening point than the original rosin, and so taught as spreading better on the fibers.
EP-A-333,368 discloses a method for sizing paper at a neutral or alkaline pH with rosin, an aluminum compound, and a cationic or anionic polyelectrolyte. The method comprises preparing and applying a preblend of the size just prior to use.
There are numerous examples of stable rosin dispersions using anionic or nonionic surfactants, whereby the fixation of the hydrophobic rosin size to the pulp fibers is augmented by the concomitant use of cationic polymers, such as starch, polyamines polyamide epihalohydrin polymers, and cationized polyacrylamides. Exemplary compositions are described, for example, in JP 61-113898 and EP 259671.
GB 2,159,183 discloses mixtures of rosin dispersion and aluminum polyhydroxy chloride. These mixtures rely for their cationicity on the formation of a stable flocculent resulting from the reversal of charge in the double layer of the colloidal particles in the dispersion.
JP-A-3294596 discloses a cationic rosin sizing agent emulsified with a polyamide-polyamine epichlorohydrin resin having hydrophobic groups. The sizing agent is used in neutral pH paper manufacturing, and is more particularly synthesized from (a) polyalkylenepolyamines, (b) dicarboxylic acids or derivatives, (c) epichlorohydrin, and at least one hydrophobic group-introducing compound selected from (d-1) monobasic carboxylic acids, their anhydrides, and their ester, (d-2) alkylamines, (d-3) alkyl ketene dimer, (d-4) alkyl- or alkenylsuccinic anhydrides, (d-5) alkylene oxides, (d-6) organic halides, and (d-7) terpenoids and derivatives.
U.S. Pat. No. 4,036,821 describes a process for the production of basic, storage-stable polyaminoamides and retention agents for fillers and pigments, drainage accelerators, and effluent-treating agents in the manufacture of paper. The process essentially comprises (a) reacting a polyfunctional compound (e.g., epichlorohydrin) with a tertiary, monofunctional amine (e.g., e.g., trimethylamine) to form an ammonium compound, and then (b) reacting the ammonium compound with the secondary amino groups in a basic polyaminoamide derived from (i) a dicarboxylic acid, (ii) a polyalkylenepolyamine, and (iii) an amino carboxylic acid or a lactam.